In simple words this is a way to have access to admin panel without asking a client for credentials. If you have FTP without credentials to admin panel you can install plugin and you will have hidden secure access. This is very helpfull for team of developers too.

same with robthecomputerguy, Looks interesting but does not tell what this item is really for.

I have lots of wp site and this looks interesting to me but after looking at the code and reading the description, I still can’t visualize how this is helpful. Perhaps giving more details to the project will increase the sales.